Utilizing a Power Stressed state causes the user to use up energy and stamina at a rapid rate in exchange for increased power. By pushing it even further, the user can gain more power but at the cost of speed. The power of this state causes the user's muscles to bulk up.
Due to his Saiyan DNA, Cell can assume his own Power Stressed form, which he does to display to Future Trunks the flaws inherit in the form, and later when enraged at Super Saiyan 2 Gohan overpowering him.
After forcefully spreading his disfigurement via the Light of Justice, Fusion Zamasu (who was in a Super Saiyan Rosé state) enters into a Power Stressed state via his anger, resulting in him almost being defeated by Vegito due to the decrease in speed he gained in exchange for his drastic increase in power.